Schiff base carbamates



United States Patent 3,012,068 SCHIFFBASE CARBAMATES Alexander T.Shnlgin, Berkeley, Calif., assignor to The Dow Chemical Company,Midland, Mich., a corporation of Delaware N0 Drawing. Filed Apr. 11,1960, Ser. No. 21,080 7 Claims. (Cl. 260-482) This invention isconcerned with Schiff base carbamate ester having the formula wherein Arand Ar represent substituted phenyl radicals and wherein one of Ar andAr is substituted with a methylcarbamoyloxy radical, OCONHCH and each ofAr and Ar may be substituted with a radical selected from the groupconsisting of chloro, bromo, fluoro, nitro, lower alkyl, lower alkoXyand di(low-alkyl)amino. By the expression lower in lower alkyl and loweralkoxy is meant groups containing from 1 to 4 carbon atoms, inclusive.

The compounds of the present invention are crystalline solids, glasses,or oily liquids soluble in many organic solvents such as benzene,toluene, xylene, methanol, ethanol, isopropyl alcohol, methylenechloride and carbon tetrachloride and substantially insoluble in water.

The products of the present invention are useful in many agriculturalapplications. They are useful as toxic constituents of parasiticidecompositions and are adapted to be employed for the control of insects,fungi, helminths, mites, bacteria, aphids and nematodes. They are alsouseful for the control of aquatic pests such as snails and trash fish.Certain of the compounds are useful in agronomical practice for thecontrol of Weeds and for inhibition of nitrification.

The compounds of particular interest are those having the formula 5-OCONHCH: I I Z In this and succeeding formulas, X represents a radicalon the phenyl ring holding the methylcarbaxoyloxy radical, OC'ONHCH Yand, Z represent radicals on the other phenyl ring; wherein each X andeach Y are selected from the group consisting of lower alkyl, loweralkoxy, bromo, chloro, fluoro and nitro; Z is a di(loweralkyDaminoradical; x and y are from 0 to 3, inclusive; 1 is from O to 1 andwherein each ring contains no more than three substituents selected fromOCONHCH X, Y and Z.

The Schiil base carbamate esters of the present invention may beprepared by (l) the reaction of an appropriate aldehyde compound with anappropriate amine compound, i.e., (a) a benzaldehyde compound with anaminophenol compound, or (b) a hydroxybenzaldehyde compound with ananiline compound to produce an intermediate Schiff base phenol and waterof reaction followed by (2) the reaction of the intermediate Schiff basephenol with methyl isocyanate, CH NCO, usually in the presence of abasic catalyst. The selection of the aldehyde compound and the aminecompound in step (1) of the reaction above depends on the particularbenzene ring in which his desired to have the methylcarbamoyloxyradical. Thus, (a) under (1) above is followed if the ultimate productis to have the methylcarbamoyloxy radical on the benzene ring holdingthe nitrogen of the Schifi base linkage, -N=CH-; however, if theultimate product is to have the methylcarbamoyloxy radical on the ringholding the carbon of the Schifi base linkage, (b) under (1) above is tobe followed. The amine compound above, i.e., the aminophenol com-3,012,068 Patented Dec. 5, 1961 pound or the aniline compound, may beemployed as its hydrohalide sat. By hydrohalide is meant hydrochlorideor hydrobrornide.

By the expression benzaldehyde compound as herein employed is meant anappropriate substituted aromatic aldehyde of the benzene series, saidaldehyde containing no hydroxy substituents. Representative benzaldehydecompounds include benzaldehyde anisaldehyde, o-nitro benzaldehyde,o-bromobenzaldehyde, p-bromobenzaldehyde, m-bromobenzaldehyde,2,6-dichlorobenzaldehyde, 2,3 dichlorobenzaldehyde, 3,4diethoxybenzaldehyde, m diethylaminobenzaldehyde,p-diethylaminobenzaldehyde, 2,3-dimethoxybenzaldehyde,2,4-dimethoxybenzaldehyde, 2,4-dimethylbenzaldehyde,2,5-dimethylbenzaldehyde, 2,6-dimethylbenzaldehyde,3,4-dimethylbenzaldehyde, 3,5-dimethylbenzaldehyde,3,4-dinitrobenzaldehyde, m dipropylaminobenzaldehyde,p-ethoxybenzaldehyde, 3 ethoxy-Z-methoxybenzaldehyde,3-ethoxy-4-methoxybenzaldehyde, 4-ethoxy 3 methoxybenzaldehyde,p-isopropoxybenzaldehyde, 4-isopropylbenzaldehyde,3-methoxy-2-nitrobenzaldehyde, 4-methoxy 2 nitrobenzaldehyde,4-bromo-2-nitrobenzaldehyde, 4-but0Xy-3-eth0xybenzaldehyde, 4 tertiarybutylbenzaldehyde, 4-(butylisobutylamino) benzaldehyde,S-chloro-Z-methoxybenzaldehyde, 2-chloro-4-nitrobenzaldehyde,2-chloro-5-nitr0- benzaldehyde, 4-dimethylamino 3 nitrobenzaldehyde, 4nitro-2-propoxybenzaldehyde, 2-chloro-6-fluorobenzaldehyde,2,6-difluorobenzaldehyde, 2,4,6triisopropylbenzaldehyde,2,3,4-trimethoxybenzaldehyde, 2,3,4-trimethylbenzaldehyde,2,4,6-trinitrobenzaldehyde, 2,6-dimethy1- 4 methoxybenzaldehyde,4,5-dimethoxy-2-nitrobenzaldehyde, 2,4,S-trichlorobenzaldehyde and2,3,6-trichlorobenzaldehyde.

By the expression aminophenol compound as herein employed is meant anappropriate aromatic aminophenol of the benzene series. Representativeaminophenol compounds include 2 aminophenol, 3 aminophenol,4-aminophenol, 2-amino-4-bromophenol, 2-amino-4-tertiary-butylphenol,5-amino-2-normal-bu-tylphenol, Z-amino-4-chloropheno1,Z-amino-S-chlorophenol, 2-amino-6- chlorophenol,Z-amino-6-chloro-4-nitrophenol, Z-amino- 4,6-dibromophenol,4-amino-3,S-dichlorophenol, 2-ami- 'no-5chloro-4-methoxyphenol,4-amino-3,S-diethylphenol, 2-amino-4,6-dinitrophenol, 3-amino 2,4dinitrophenol, 2-amino-4-ethylphenol, 4-amino-3-fluorophenol, Z-amino-4-isobutylphenol, 2-amino-4-isopropylphenol, 2-amino-4- methoxyphenol,2-amino-4-nitrophenol, 3-amino-4-propylphenol, 4-amino-3,5-Xylenol,Z-amino 3,5 Xylenol, 2-amino-4-chloro-S-nitrophenol, 6-amino-2,4-Xy1eno1and 4-amino-5-ethyl-m-cresol.

By the expression hydroxybenzaldehyde compound" as herein employed ismeant an appropriate aromatic aldehyde of the benzene series having ahydroxy substituent and which may contain other substituents.Representative hydroxybenzaldehyde compounds include 3 4-hydroxy-3-nitrobenzaldehyde, -hydroxy-2-nitrobenzaldehyde,2-bromo-3-hydroxy-4-methoxybenzaldehyde, 6-bromo-3-hydroxy-4-methoxybenzaldehyde, 5-bromosalicylaldehyde,3-chiorosalicylaldehyde, 5 -chlorosalicylaldehyde,3,5-dibromosalicylaldehyde, 3 ,5 -dichlorosalicylaldehyde,3,4-dimethoxysalicylaldehyde, 4,6-dimethoxys alicylaldehyde,4,6-dirnethylsalicylaldehyde, 3,5-dinitrosalicylaldehyde,3-ethoxysalicylaldehyde, S-fluorosalicylaldehyde,,3rmethoxysalicylaldehyde, 4-methoxysalicylaldehyde,.6-methoxysalicylaldehyde, 3-nitrosalicylaldehyde,4-nitrosalicylaldehyde, .3-propyls alicylaldehyde, 6-bromo-4-hydroxy-3-methoxybenzaldehyde, 6-chloro-4-hydroxy-3-methoxybenzaldehyde,4-hydroxy-2-methyl-5-propylbenzaldehyde,5-chloro-3-fluorosalicylaldehyde, 3 ,6-dimethylsalicylaldehyde,p-thymolaldehyde and salicylaldehyde.

By the expression aniline compound as herein employed is meant anappropriate aromatic amine of the benzene series, said amine containingno hydroxy substituent. Reprmentative compounds include aniline, 3--bromoaniline, Z-bromoaniline, 4-bromoaniline, 2-bromo- -6-ethylaniline,2-bromo-5-nitroaniline, 3-bromo-4-nitroaniline, 4-bromo-3-nitroaniline,5-bromo-2-nitroaniline, 2-butoxy-5-nitroaniline,4-but0xy-3-nitroaniline, 4second- :ary butylaniline,4-tertiary-butyl-2-nitroaniline, 3-chloroaniline,2-chloro-3-nitroaniline, 2- chloro-4-nitroaniline 2,4-dibromoaniline,3,5-dibromoaniline, 3,4-dibutoxyaniline, 2,4-dichloroaniline,3,5-dichloroaniline, 3,4-diethylaniline, 2,4-difiuoroaniline,2,5-diisopropylaniline, 2,4-diisopropylaniline, 2,3-dimethoxyaniline,3,4-dimethoxyaniline, 2,3-dinitroaniline, 2,4-dinitroaniline,3-ethylaniline, 2-fluoroaniline, 4-fluoroaniline,2-fluoro-4-nitroaniline, 3- fl'uoro-4-nitroaniline,4-isobutyl-3-nitroaniline, 2-isopropoxy-S-nitroaniline,3-isopropylaniline, line, 2-isopropyl-S-methylaniline,5-isopropyl-2-methylaniline, 3-nitroaniline, 2-nitro-4-propoxyaniline,4-nitro- 3-propoxyaniline, 2-ethyl-3-methoxyaniline, methoxyaniline,3-rnethoxy-4-methylaniline, 3-methoxy- S-nitroaniline,S-bromo-2-methoxyaniline, 3 -chloro-2- .methoxyaniline,3-fluoro-2methoxyaniline, 2-bromo-4,6- diethylaniline, 2-bromo 3,4dimethoxyaniline, 2,6-dibromo-4-fluoroaniline,4,5-dibromo-2-nitroaniline and 2,4- diisopropyl-S-nitroaniline.

The first step of the reaction may be carried out by reactingsubstantially equimolar proportions of the appropriate benzaldehydecompound or hydroxybenzaldehyde compound with correspondingly theappropriate aminophenol compound or aniline compound, or the hydrohalidesalt of the aminophenol or aniline compound. The reaction is usuallycarried out in the presence of a solvent or liquid reaction medium overa period of from about 5 minutes to 24 hours in the temperature range offrom about 15 to 100 C. with the formation of the desired Schifi basephenol intermediate and water of reaction. The preferred conditions forcarrying out the preparation of the Schiif base phenol intermediatedepends in part on whether the aniline or aminophenol compound isemployed as a free base or as its hydrohalide salt.

In one method of carrying out thisstep, the appropriate aldehydecompound is added to an aqueous solution of the appropriate aminehydrohalide compound. (The latter is prepared by dissolving theappropriate amine in suificient dilute hydrohalic acid to maintain theamine in 4-isopropylanisolution as its hydrohalic acid salt or bydissolving the amine hydrochloride or hydrobromide in Water.) Thereaction mixture is agitated to insure complete dispersion of thealdehyde and allowed to react at a temperature of from about 20 to 60 C.for a period of from about 0.25 to 2 hours. At the end of this period,sodium acetate is added to the reaction mixture whereupon a Schifi basephenol intermediate precipitates as a solid or anoil. The sodium acetatemay be added as a solid or as an aqueous solution over a period of fromabout 5 minutes to 30 minutes. The Schilf base phenol intermediate maybe recovered from the reaction mixture by conventional pro-' ceduressuch as filtration, decantation or extraction with an appropriateWater-insoluble solvent such as ether or methylene chloride and maythereafter be purified, if desired, by Washing, decolorizing asolutionthereof with activated charcoal and/or by recrystallization. Suitablesolvents for recrystallization include pentane, hexane, isooctane,carbon tetrachloride, methanol, ethanol, isopropyl alcohol andalcohol-Water combinations.

In an alternative method for carrying out the first step and preferredfor preparing a Schifr base phenol derived from a hydroxybenzaldehydecompound and an aniline compound, substantially equirnolar proportionsof the appropriate reactants are mixed together in an organic solventand the resulting mixture heated at reflux temperature from about 0.25to 1.0 hour to obtain the desired Schiff basephenol intermediate andWater of reaction. Suitable solvents include ethanol, propanol, butanoland benzene. After completion of the reaction, the Schifi base phenolintermediate is recovered from the reaction mixture by conventionalprocedures, the most suitable method depending on the solvent employed.Thus, when benzene is the solvent, the Water of reaction is co-distilledwith the organic solvent, excess organic solvent distilled off andSchiff base phenol intermediate recovered as residue. When alcoholicsolvent is employed, the Schifi base phenol intermediate usuallyprecipitates in the reaction mixture and may be recovered by filtration;alternatively, the solvent and water may be'vaporized off and theintermediate recovered as residue. The latter may be purified, ifdesired, by conventional procedures as previously set V forth.

residue by evaporating or distilling oil? the solvent.

In the second step for carrying out the preparation of the compounds ofthe invention, a substantially equimolar proportion or an excess ofmethyl isocyanate is mixed together and reacted With a Schiff basephenol intermediate prepared as above described at a temperature of from0 to 40 C. for a period of from 1 to 48 hours. The reaction ispreferably carried out in the presence of a catalyst and a solvent.Suitable catalysts include triethylamine, pyridine, picoline andcollidine. A suitable amount of catalyst is considered to be about 3 to4 drops per gram of Schiff base phenol employed although frequentlylarger amounts are desirable. Preferred solvents are methylene chlorideand dimethylformamide. For manypreparations Where solubility of theSchiif base phenol permits, pentane, hexane and other hydrocarbonsolvents may be employed. Alternatively, the reaction may be carried outin excess triethylamine, pyridine, picoline or collidine, said basesfunctioning both as a catalyst and as a solvent. As a result of theseoperations, the desired Schiff base carbamate product is formed. Thelatter usually precipitates in the reaction mixture but may remain insolution. The product may be recovered by filtration if it precipitatesas a solid, or as The product may then be purified by Washing ordecolorizing with activated charcoal and by recrystallization from asuitable solvent such as'methylene dichloride, pentane, hexane,isooctane or a mixture thereof. The products in which themethylcarbamoyloxy group is in the meta position with respect to theSchiff base linkage,

-N=CH-, tend to be glassy solids or viscous liquids.-

The glassy solids are not readily recrystallized, and the preferredmethod of purification is grinding the glassy solid in an inert solvent.

In a preferred method for carrying out the prepmation of the compoundsof the invention derived from a benzaldehyde compound and an aminophenolcompound, an appropriate benzaldehyde compound is added to an aqueoushydrochloric acid solution of the appropriate aminophenol compound.After completion of the addition, the mixture is shaken vigorously forfrom about 15 minutes to 1 hour and sodium acetate added theretowhereupon a reaction takes place with the formation of the desiredSchiil base phenol intermediate. The latter is recovered from thereaction mixture and purified, if desired, as previously described.

The Schifi base phenol thus prepared is mixed with methyl isocyanate inmethylene chloride or dimethylformarnide solvent and a few drops oftriethylamine catalyst added thereto. The resulting mixture is allowedto stand at to 40 C. for from 1 to 48 hours whereupon a reaction takesplace with the formation of the desired Schiff base carbamate product.The latter is recovered by filtration or by vaporizing off the solventand thereafter purified, if desired, by conventional procedures.

In a preferred method for carrying out the preparation of the compoundsof the invention derived from a hydroxybenzaldehyde compound and ananiline compound, the appropriate hydroxybenzaldehyde compound and theappropriate aniline compound are mixed together and heated at refluxtemperature for-from about 15 minutes to 1 hour to obtain the desiredSchifi base phenol intermediate. The latter is recovered from thereaction mixture and purified, if desired, as previously described. TheSchifi base phenol intermediate is then reacted with methyl isocyanateas above described.

The following examples illustrate the invention but are not to beconstrued as limiting.

EXAMPLE 1 4-benzylidelzeaminO-S-terriary-butylphenyl methylcarbamate2.12 grams (0.02 mole) of benzaldehyde was added to a solution of 3.30grams (0.02 mole) of 4-amino-3- tertiary-butylphenol in 2% percentexcess (molar basis) of 1 normal hydrochloric acid. The resultingheterogeneous mixture was shaken and then treated with a solution of2.92 grams of sodium acetate tn'hydrate in 20 milliliters of water. Anoily phase immediately formed which crystallized upon repeated washing(by decantation) with cold water to produce a4-benzylideneamino-3-tertiary=butylphenol intermediate as a yellowgreensolid melting at 121122 C.

A solution of 3.0 grams (0.012 mole) of the above 4-benzylideneamino-3-tertiary-butylphenol in milliliters warm methylenechloride was diluted with 30 milliliters of warm hexane. To this nearlysaturated solution was added 0.68 gram (0.012 mole) of methyl isocyanateand 3 drops of triethylamine. The mixture was allowed to stand at roomtemperature over the Weekend whereupon the desired4-benzylideneamino-3-tertiary-butylphenyl methylcarbamate productprecipitated as rosettes of yellow-green crystals. The latter melted at109.5111 C. and amounted to a yield of 3.1 grams.

EXAMPLE 2 4-benzylideneaminophenyZ methylcarbamate 20.5 milliliters(21.5 grams; 0.2 mole) of benzaldehyde was added to a solution of 21.8grams (0.2 mole) of p-aminophenol in 200 milliliters of 1normal-hydrochloric acid. The mixture was agitated and a solution of29.2 grams sodium acetate trihydrate in 100milli- CHsNHC O O 6 liters'of water added thereto. A' reaction took place with the precipitation ofcrystals of a 4-benzylideneaminophenol intermediate. The latter wasrecovered by filtration and recrystallized from 50 percent ethanol toobtain yellow to yellow-brown crystals having a melting point of183.5l84.5 C.

19.3 grams (0.1 mole) of the above 4-benzylideneaminophenol intermediatewas dissolved in 450 milliliters of triethylamine and 5.7 milliliters(0.1 mole) of methyl isocyanate added thereto. The reaction mixture wasallowed to stand for an hour, the solvent then partially evaporatedunder reduced pressure therefrom and the resulting mixture allowed tostand overnight at 0 C. to precipitate the desired4-benzylideneaminophenyl methylcarbamate product as fine yellow crystalsmelting from 106 to 110 C. A sample recrystallized from a mixture ofmethylene chloride-hexane had a melting point of113-115 C.

EXAh/IPLE 3 4-(2,4-dicklorobenzylideneamino)-3,5-xylyl methylcarbamateIn a similar manner as previously described, 8.75 grams (0.05 mole) of2,4-dichlorobenzaldehyde and a solution of 7.3 grams of sodium acetatetrihydrate were added in successive steps to a solution of 6.85 grams(0.05 mole) of 4-amino-3,5-xylenol in 50 milliliters of 1 normalhydrochloric acid to obtain an intermediate 4-(2,4-dichlorobenzylideneamino)-3,5-xylenol as a yellowbrown solid. Thelatter after repeated recrystallization from pentane-methylenechloridemelted at C.

0.25 milliliter (0.0044 mole) of methyl isocyanate and a drop oftriethylamine catalyst were added to a solution of 1.0 gram (0.0034mole) of the above 4-(2,4-dichlorobenzylideneamino)-3,5-xylenolintermediate in 3 milliliters of dimethylformamide. The resultingreaction mixture was warmed to remove the solvent and to recover asresidue a 4-(2,4-dichlorobenzylideneamino)-3,5- xylyl methylcarbamateproduct which on recrystallization from methylene chloride-pentanemelted at 136'138 C.

EXAMPLE 4 In a manner similar to that previously described, thefollowing Schitf base carbamates were prepared:

4-(4-chlorobenzy1ideneamino) 3 tertiary-butylphenyl methylcarbamate asyellow crystals melting at 148- 150 C. by the reaction of4-chlorobenzaldehyde with 4-amino-3-tertiary-butylphenol to produce anintermediate 4-(4-chlorobenzylideneamino)-3-tertiary-butylphenolfollowed by the reaction of the latter with methyl isocyanate.

4-(2,4-dichlorobenzylideneamino) 3 tertiary butyl methylcarbamate asyellow crystals having a melting point of 124125 C. by the reaction of2,4-dichlorobenzaldehyde with 4-amino-3-tertiarybutylphenol to producean intermediate 4-(2,4-dichlorobenzylideneamino)- S-tertiary-butylphenolfollowed by the reaction of the latter with methyl isocyanate.

4-benzylideneamino-3,S-xylyl methylcarbamate as yellow crystals meltingfrom 11-1-113 C. by the reaction of benzaldehyde with4-amino-3,5-xylenol to produce an intermediate4benzylideneamino-3,5-xylenol followed by the reaction of the latterwith methyl isocyanate.

4-(4-chlorobenzylideneamino)-3,5-xylyl methylcarbamate melting from 188to C. by the reaction of 4-chlorobenzaldehyde with 4-amino-3,5-xylenolfollowed by the reaction of the latter with methyl isocyanate.

4- (4-dimethylaminobenzylideneamino -3 ,S-xylyl methylcarbamate meltingat 156 C. by the reaction of 4-di methylaminobenzaldehyde with4-amino-3,5-xylenol to produce an intermediate4-(4-dimethylarninobenzylidene amino)-3,5-xylenol followed by thereaction of the latter with methyl isocyanate.

2-benzylideneaminophenyl methylcarbamate as white granular crystalsmelting at l26-127 C. by the reaction of benzaldehyde with Z-aminophenolto produce an intermediate Z-benzylidenearninophenol followed by thereaction of the latter with methyl isocyanate.

r2-(4-chlorobenzylideneamino)phenyl methylcarbamate melting from 149 to15 6 C. by the reaction of 4-chlorobenzaldehyde with 2-aminophenol toproduce an intermediate 2-(4-chlorobenzylideneamino)phenol followed bythe reaction of the latter with methyl isocyanate.

2-(2,4 dichlorobenzylideneamino)phenyl methylcarbamate melting from 121to 126 C. by the reaction of 2,4-dichlorobenzaldehyde with 2-aminophenolto produce an intermediate 2-(2,4-dichlorobenzylideneamino)phenolfollowed by the reaction of the latter with methyl isocyanate.

2-(4-dimethylaminobenzylideneamino)phenyl methylcarbamate having amelting point of 157-l59 C. by the reaction of 4dimethylaminobenzaldehyde with Z-aminophenol to produce an intermediate2-(4-dimethylaminobenzylideneammo)phenol followed by the reaction of thelatter with methyl isocyanate.

2-(4-bromobenzylideneamino)phenyl methylcarbamate having a melting pointof l66l67 C. by the reaction of 4-bromobenzaldehyde with 2-aminophenolto produce an intermediate 2-(4-bromobenzylideneamino)phenol followed bythe reaction of the latter'with methyl isocyanate.

2-(3-fluorobenzylideneamino)phenyl methylcarbarnate having a meltingpoint of 118.5 -120 C. by the reaction of 3-fluorobenzaldehyde andZ-aminophenol to produce an intermediate2-(3-fiuorobenzylideneamino)phenol followed by the reaction of thelatter with methyl isocyanate.

2-(2-nitrobenzylideneamino)phenyl methylcarbamate having a melting pointof 148-149 C. by the reaction of Z-nitrobenzaldehyde with Z-aminophenolto produce the intermediate 2-(2-nitrobenzylideneamino)phenol fol- Vlowed by the reaction of the latter with methyl isocyanate.

EXAMPLE 5 2-(4-nitrobenzylideneamino) -4-nitrophenyl methylcarbamale OCONHOH:

3.8 grams (0.025 mole) of 4-nitr0benzaldehyde was added to a boilingsolution of 3.9 grams (0.025 mole) of 2-amino-4-nitrophenol in about 20milliliters of ethanol. The mixture was heated at reflux temperature fora few minutes and thereafter cooled to 0 C. to obtain as a precipitate4.0 grams of a 2-(4-nitrobenzylideneamino)- 4-nitrophenol intermediateas drab-green crystals, melting at 232 ,C. with decomposition.

0.39 milliliter (0.0067 mole) of methyl isocyanate and four drops oftriethylamine were added to a solution of 0.98 gram of the2-(4-nitrobenzylideneamino)-4-nitrophenol above prepared in milliliters.of methylene chloride. A reaction took place with slight heating andthe formation of a desired 2-(4-nitrobenzylideneamino)- 4-nitrophenylmethylcarbamate product which precipitated in the reaction mixture as acrystalline solid. The latter was recovered by filtration and washedwith pentane to obtain a purified product as a dull green solid meltingat 215 0.

EXAMPLE *6 In reactions carried out in a manner similar to thatdescribed in Example 5, the following compounds are prepared:

' Z-benzylideneamino-4-nitrophenyl methylcarbamate as .-a rust orangesolid melting at 233 C. with decomposition by the reaction ofbenzaldehyde with 2-amino-4- nitrophenol to produce the intermediateZ-benzylideneamino-4-nitrophenol followed by the reaction of the latterwith methyl isocyanate.

2-(4 chlorobenzylideneamino)-4-nitrophenyl methylcarbamate as a tansolid melting at 143 l44 C. by the reaction of 4-chlorobenzaldehyde with2-amino-4-nitrophenol to produce the intermediate2-(4-chlorobenzylideneamino)-4-nitrophenol followed by the reaction ofthe latter with methyl isocyanate.

2-(4-dimethylaminobenzylideneamino) 4 nitrophenyl methylcarbamate as anolive-green solid melting at 227- 227.5 C. by the reaction of4-dimethylaminobenzaldehyde with 2-amino-4-nitrophenol to produce theintermediate 2-(4 dimethylaminobenzylideneamino)-4-nitrophenol, followedby the reaction of the latter with methyl isocyanate.

2-(4-bromobenzylideneamino) 4 nitrophenyl methylcarbamate as apurplish-gray crystalline solid melting at l63-163.5 C. by the reactionof 4-bromobenzaldehyde with 2-ar'1ino-4-nitrophenol to produce theintermediate 2-(4-bromobenzylideneamino)-4-nitrophenol followed by thereaction of the latter with methyl isocyanate.

2-(4-isopropylbenzylideneamino) phenyl methylcarbamate having amolecular weight of 296 by the reaction of 4-isopropylbenzaldehyde withZ-aminophenol to produce the intermediate2-(4-isopropylbenzylideneamino)- phenol followed by the reaction of thelatter with methyl isocyanate.

2-(3-methoxybenzylideneamino)phenyl methylcarbamate having a molecularweight of 284 by the reaction of 3-methoxybenzaldehyde with2-aminophenol to pro duce the intermediate2-(3-methoxybenzylideneamin0)- phenol followed by the reaction of thelatter with methyl isocyanate.

EXAMPLE 7 3 3-nitr0b enzylideneamino phenyl methylcarbamate C HsNH C ONO 2 3.02 grams (0.020 mole) of 3-nitrobenzaldehyde was added to asolution of 2.18 grams of 3-aminophenol (0.020 mole) in 10 millilitersof hot butanol. The mixture was heated at the boiling point for 5minutes after which the butanol was removed at C. with an air stream toobtain a-solid residue. The latter was ground under ether (withsubsequent removal of the ether at 100 C.) to obtain 5.01 grams of a3-(3-nitrobenzylideneamino)phenol intermediate as a gold-colored solidwith a melting point higher than 300 C.

1.0 milliliter (0.028 mole) of methyl isocyanate and four drops oftriethylamine were added with stirring to a solution of 2.5 grams (0.01mole) of the 3-(3-nitrobenzylideneamino) phenol intermediate prepared asabove described in 20 milliliters of dimethylformamide. The resultingmixture was allowed to stand overnight at room temperature andthereafter the dimethylformamide removed by vaporization under reducedpressure to obtain a desired 3(3-nitrobenzylideneamino)phenylmethylcarbamate product as a glassy solid residue. The latter was groundin methylene chloride to obtain a purified prodnet as a yellow powdermelting at 240 C. with decomposition.

EXAMPLE 8 In reactions carried out in a similar manner, the followingcompounds were prepared:

3-benzylideneaminophenyl methylcarbarnate as a tan solid melting at 240C. with decomposition by the reaction of benzaldehyde with3-aminophenol, followed by the reaction of the latter with methylisocyanate.

3 (2,4 dichlorobenzylideneamino)phenyl methylcarbamate as a tan solidmelting at 137 C. with decomposition by the reaction of2,4-dichlorobenzaldehyde with 3- aminophenol, followed by the reactionof the latter with methyl isocyanate.

3 (3,4 diethoxybenzylideneamino)phenyl methylcarbamate as a very viscousgold-colored oil having a molecular weight of 342 by the reaction of3,4-diethoxybenzaldehyde with 3-aminophenol, followed by the reaction ofthe latter with methyl isocyanate.

EXAMPLE 9 a- (4-dimethyZam'inophenylimino) -o-tolyl methylcarbamate o CONHCH;

6.1 grams (0.05 mole) of salicylaldehyde and 6.8 grams (0.05 mole) of4-dimethylaminoaniline and 100 milliliters of benzene were mixedtogether and the resulting mixture heated to distill off the water ofreaction as a benzene-water azeotrope, the benzene being replaced as itwas distilled ofi. The remaining benzene was then distilled off and theoily residue poured onto a glass plate wherein it set to a hard darksolid. The latter was triturated with ethanol to obtain ana-(4-dimethylaminophenylimino)-o-cresol intermediate as orange plateletsmelting at 135-136.5 C.

3.0 grams (0.0125 mole) of the abovetx-(4-dimethylaminophenylimino)-o-cresol intermediate was dissolved in25 milliliters of methylene chloride and 0.9 milliliter (0.016 mole) ofmethyl isocyanate and a drop of triethylamine added thereto. The mixturewas allowed to stand for a day at room temperature and the solvent thenflashed off on a steam bath to produce 2.0 grams of an a-(4dimethylaminophenylimino)-o-tolyl-methylcarbamate product as brightyellow crystals having a melting point of l50-151 C.

EXAMPLE l u-(4-chlorophenylimino)-0-t0lyl methylcarbamate In a similarmanner, an a-(4-chlorophenylimino)-ocresol intermediate as glisteningorange crystals having a melting point of 100-102 C. was prepared fromsilicylaldehyde and 4-chloroaniline.

1.05 milliliters (0.0184 mole) of methyl isocyanate and a few drops oftriethylamine were added to a solution of 3.60 grams (0.0155 mole) ofthe a-(4-Chl0l0- phenylimino)-o-cresol intermediate prepared as abovedescribed in 20 milliliters of methylene chloride and the resultingmixture allowed to stand at room temperature for two days. At the end ofthis period, a major portion of the solvent was removed by vaporizationto obtain an at (4 chlorophenylimino)-o-tolyl methylcarbamate product asprecipitate. The latter was recovered by filtration and was found to bea white prismatic solid. The melting point of the product was 185 188 C.

EXAMPLE 11 In reactions carried out similar to that described in Example9, the following methylcarbamates were prepared:

a-Phenylimino-o-tolyl methylcarbamate melting from 89 -93 C. by thereaction of salicylaldehyde and aniline to produce an intermediatea-phenylimino-o-cresol followed by the reaction of the latter withmethyl isocyanate.

oz-(Z-chlOrOphenYlitfninO)-0-'tOlyl methylcarbamate as a white solidhaving a melting point of 165 -167 C. by the reaction of salicylaldehydewith 2-chloroaniline to produce an intermediate0c-(Z-ChlOIOPhEHYIimiBO)-O-C1S0l followed by the reaction of the latterwith methyl isocyanate.

u-(3-chlorophenylimino)-o-toly1 methylcarbamate as a white solid meltingfrom 1131l6 C. by the reaction of salicylaldehyde with 3-chloroanilineto produce an intermediate a-(3-chlorophenylimino)-o-cresol followed bythe reaction of the latter with methyl isocyanate.

' a- (2,4 dichlorophenylimino)-o-tolyl methylcarbamate' as yellowcrystals having a melting point of 125 126 C. by the reaction ofsalicylaldehyde with 2,4-dichloroaniline to produce an intermediatea-(2,4-dichlorophenylimino)-o-cresol followed by the reaction of thelatter with methyl isocyanate.

a-(2,5-dichlorophenylimino) -o-tolyl methylcarbamate as while prismsmelting from 162166 C. by the reaction of salicylaldehyde with2,5-dichloroaniline to produce an intermediatea-(2,5-dichlorophenylimino)-o-cresol followed by the reaction of thelatter with methyl isocyanate.

a-(3,4-dichlorophenylimino)-o-tolyl methylcarbamate as white granularsolid melting from l40143 C. by the reaction of salicylaldehyde with3,4-dichloroaniline to produce an intermediatem-(3,4-dichlorophenylimino)-ocresol followed by the reaction of thelatter with methyl isocyanate.

a-(4-tolylimino)-o-tolyl methylcarbamate as a creamcolored solid meltingfrom 130l33 C. by the reaction of salicylaldehyde with 4-methylanilineto produce an intermediate a-(4-tolylimino)-o-cresol followed by thereaction of the latter with methyl isocyanate.

EXAMPLE 12 a-(2,5-dimethoxyphenylimino)-m-t0lyl methylcarbamate (KGB: 0OONHCHa In a manner similar to that described in Example 7, ana-(2,5-dimethoxyphenylimino)-m-cresol intermediate having a meltingpoint of 97 98 C. was prepared by the reaction of S-hydroxybenzaldehydeand 2,5-dimethoxyaniline.

0.75 milliliter (0.013 mole) of methyl isocyanate and four drops oftriethylamine were added with agitation to a solution of 2.5 grams(0.0097 mole) of the 0L-(2,5 dimethoxyphenylimino)-m-cresol intermediateabove prepared in 15 milliliters of methylene chloride. The resultingmixture was allowed to stand at room temperature for.

24 hours and the solvent thereafter removed by vaporization to obtain ana-(2,5-dimethoxyphenylimino)-m-tolyl methylcarbamate product as a glassysolid. The latter was ground in pentane and recovered by filtration. Theproduct was a greenish-yellow solid melting from 100 C. to C.

EXAMPLE 13 a-Phenylimino-m-tolyl methylcarbamate In a manner similar tothat described in Example 7, m-phenylimino-m-cresol intermediate (M.P.83 -85C.) Was prepared from aniline and m-hydroxybenzaldehyde.

A solution in methylene chloride of 1.7 grams of the aphenylimino-m-cresol intermediate thus prepared was reacted with 1.48milliliters of methyl isocyanate in the presence of 4 drops oftriethylamiue catalyst to obtain a desired u-phenylimino-m-tolylmethylcarbamate product as a tan solid melting at 65 -66 C.

EXAMPLE 14 a- (3-chlorophenylz'mino)-p-t0lyl methylcarbamate In a methodsimilar to that described in Example 5, 24.4 grams (0.20 mole) of4-hydroxybenzaldehyde and 25.5 grams (0.20 mole) of 3-chloroaniline werereacted in milliliters of boiling ethanol to obtain 32.8 grams of anu-(3-chlorophenylimino)-p-cresol intermediate as a pale yellow solid.

2.45 milliliters (0.043 mole) of methyl isocyanate and four drops oftriethylamine were added with agitation 1 1 to a solution of 5.0 grams(0.022 mole) of the a-(3- chlorophenylirnino)-p-cresol intermediateprepared as above described in 20 milliliters of methylene chloride toobtain an a-(3-chlorophenylimino)p-tolyl methylcarbarnate product whichprecipitated in the reaction mixture as a crystalline solid. Thereaction mixture was allowed to stand overnight and the productrecovered by filtration and washed with pentane. The latter was a flulfycrystalline solid melting at l34l35 C.

EXAMPLE 15 In similar preparations, the following compounds wereprepared:

'a-Phenyliminop-tolyl methylcarbamate as a tan, crystalline solidmelting at 103 l04 C. by the reaction of 4-hydroxybenzaldehyde andaniline to produce an aphenyliminop-cresol intermediate, followed by thereaction of the latter with methyl isocyanate.

a-(4-chlorophenylirnino)-p-tolyl methylcarbamate as a white crystallinesolid melting at l69-l70 C. by the reaction of 4-hydroxybenzaldehyde and4-chloroaniline to produce an intermediatea-(4-chlorophenylimino)-pcresol, followed by the reaction of the latterwith methyl isocyanate.

a-(4-bromo-phenylimino)-p-tolyl methylcarbamate as a white crystallinesolid melting at 1 60-l70'C. by the reaction of 4-hydroxybenzaldehydeand 4-bromoaniline to produce an intermediatea-(4-bromophenylimino)-pcresol, followed by the reaction of the latterwith methyl isocyanate.

EXAMPLE 163-(4,5-dimethoxy-Z-nitrobenzylideneamin=0)phenylmethylcarbamate OHSNHCOO-'amino)phenol intermediate having a melting'point of 0.6 milliliter(0.011 mole) of methyl isocyanate and 0.5 milliliter of triethylaminewere added to a cloudy solution of 1.5 grams (0.005 mole) of the3-(4,5-dimethoxy 2 nitrobenzylideneamino) phenol intermediate and about25 milliliters of methylene chloride. About 5 minutes after completionof the addition a reaction took place with the mixture becoming clear.The reaction mixture was allowed to stand overnight and the solventremoved by vaporization to recover as residue a 3 (4,5 dimethoxy 2nitrobenzylideneamino)phenyl methylcarbamate product as a heavy oilhaving a molecular weight of 359.

EXAMPLE 17 In similar preparations, the following compounds areprepared:

4-(3 dipropylarninobenzyl-ideneamino)phenyl methylcarbamate by thereaction of 3-dipropylaminobenzaldehyde with 4-aminophenol to producethe intermediate 4- (3-dipropylaminobenzylideneamino)phenol, followed bythe reaction of the latter with methyl isocyanate.

4-(4-butoxy-3-ethoxybenzylideneamino) 3,5 dichlorophenyl methylcarbamateby the reaction of 4-butoxy-3- ethoxybenzaldehyde with4-amino-3,S-dichlorophenol to produce the intermediate4-(4-butoxy-3-ethoxybenzylidene-amino)-3,5-dichlorophenol, followed bythe reaction of the latter with methylisocyanate.

4 (4,5-dirnethoxy-2-nitrobenzylidenearnino) 3,5 xylyl methylcarbarnateby the reaction of 4,5-dimethoxy-2- nitrobenzaldehyde and4-amino-3,5-xylenol to produce the intermediate 4-(4,5-dimeth0xy 2nitrobenzylideneamino) 3,5 xylenol followed by the reaction of thelatter with methyl isocyanate.

4 (2,4,6-triisopropylbenzy1idenearnino) 3,5 xylyl methylcarbamate by thereaction of 2,4,6 triisopropylbenzaldehyde and 4-amino-3,5-xylenol toproduce the intermediate 4-(2,4,6-triisopropylbenzylideneamino)-3,5-xylenol followed by the reaction of the latter with methyl isocyanate.

The compounds of the present invention are useful as parasiticides. Asagricultural pesticides, they give, for

example, good control of aphids and mites when infested plants aresprayed with dispersions containing the compounds as toxic ingredients.They are further useful for the control of plant fungi, soil nematodes,and as inhibitors in nitrification of reduced nitrogen in soil. Many ofthese compounds are useful as herbicides, both terrestrial and aquatic.

The compounds of the present invention have also been found to beeffective for the control of helminths attacking warm-blooded animalssuch as Bunostomum sp., Haemonchus sp., Oesophagostum sp., Ostertagisp., Trichostrongulus sp. and Cooperia sp. in representative operationsas anthelmintics, complete controls of the above helrninths wereobtained when, in separate operations, compositions containing4-benzylideneamino-3,5- xylyl methylcarbamate, 3 tertiary butyl 4t-chlorobenzylideseamino)phenyl methylcarbamate, 4(2,5-dichlorobenzylideneamino) 3,5 xylyl methylcarbamate,a-(2-chlorophenylimino)-o tolyl methylcarbamate, and4-(4-dimethylaminobenzylidenearnino) 3,5-xylyl methylcarbarnate wereapplied at a rate of 300 parts by weight per million parts ofcomposition.

The compounds of the present invention are also useful for the controlof various water pests such as trash fish, snails and entomostracans.They are further useful for the control of household pests such as fliesand cook- Eroaches as well as for the'control of bacteria and fungi.

The compounds having the structure have outstanding activity againstchewing-type insects as represented by Mexican bean beetle (Epilachnavarivestis) and Southern army worm (Prodenia e rz'danin). Inrepresentative operations for the control of chewing insects,4-benzylideneamino-3-tertiary-butylphenyl methylcarbamate, 4benzylideneamino 3,5-xylyl methylcarbamate, 3tertiary-butyl-4-(4-chlorobenzylideneamino)- phenyl methylcarbamate, 4(2,4 dichlorobenzylideneamino)-3,5-xylyl methylcarbamate, 4 (4chlorobenzylideneamino)-3,5-xylyl methylcarbamate and 4 (4dimethylaminobenzylideneamino) 3,5 xylyl methylcarbamatewere separatelydispersed in water to prepare aqueous spray compositions containing 25parts per million by weight of one of the methylcarbamates per millionparts by weight of ultimate spray mixture. These compositions wereseparately applied to a series of cranberry bean plants in amountssufiicient to wet the foliage. The leaf surfaces were then allowed todry and the plants infested with a known number of Mexican bean beetles.Three days after infestation, the plants were examined to ascertain thecontrol of Mexican bean beetle attributable to the test compounds. Itwas found that in all cases, complete kills of Mexican bean beetle wereobserved. 1 claim: 1. A Schiff base carbamate ester having the formulaAr =cH-Ar' wherein Ar and Ar represent substituted phenyl radicals 13and wherein one of Ar and Ar is substituted with a methylcarbamoyloxyradical, OCONHCH and each of Ar and Ar may be substituted with a radicalselected from the group consisting of chloro, fluoro, bromo, nitro,lower alkyl, lower alkoxy and di(lower-alkyl)amino.

2. A compound having the formula l0CONHGHa wherein X represents aradical on the phenyl ring holding the methylcarbamoyloxy radical,OCONHCH Y and Z represent radicals on the other phenyl ring; each X andeach Y are selected from the group consisting of lower alkyl, loweralkoxy, bromo, chloro, fluoro and nitro, Z is .a di(lower-alkyl)aminoradical; x and y are from 0 to 3, inclusive, z is from O to 1 andwherein each ring contains no more than three substituents selected fromOCONHCH X, Y and Z.

3. 4-benzylideneamino-3-tertiary-butylphenyl methylcarbamate.

4. 4-benzylideneaminophenyl methylcarbamate.

5. 4-(2,4-dich1orobenzy1ideneamino)-3,5-xylyl methylcarbamate.

6. a-(4-dimethylaminopheny1imino)-o-tolyl methylcarbamate.

7. 4-benzylideneamino-3,5-xyly1 methylcarbamate.

No references cited.

UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent N 3 Ol2 O68December S 196].

Alexander To Shulgin It is hereby certified that error appears in theabove numbered patent requiring correction and that the said LettersPatent should read as corrected below.

Column l line 1O for "ester" read esters -=-5 line 43,, for"methylcarbaxoyloxy" read methylcarbamoyloxg column 11, line 19 f0rl69470 0." read 166 l68 C. line for "l-l70 Cg" read 169 -170 Ca 3 columnl2, lines 30 and 31,, for "(4-=chl0robenzylideseamino)phenyl" read(4-chlorobenzylid neamin0)'phenyl Signed and sealed this 26th day ofJune 1962 (SEAL) Attest:

ERNEST w. SWIDER DAVID LADD Attesfing Officer v Commissioner of Patents

1. A SCHIFF BASE CARBAMATE ESTER HAVING THE FORMULA